重力坝加高的温度应力问题

大坝的加高将成为未来水利建设的重点之一。重力坝加高中往往会出现三个影响坝体 质量和受力的问题：坝踵应力恶化、新老混凝土结合面开裂及坝体下游面裂缝。本文讨论和分析了出现这三个问题的主要原因及解决这些问题的基本思路。通过对丹江口大坝加高的三维仿真分析，探索了通过温度控制解决加高问题的基本方法及可行性。结果表明，通过新混凝土的超冷、保温并选择适当的施工措施，可以改善坝踵应力状态，同时保证新老混凝土的结合面的大部分保持结合状态，从而保证新老混凝土的共同受力。

Thermal stress control during Heightening Gravity-Dams

The heightening technique of gravity-dams will be one of the keystones in the hydraulic construction in coming years. There are three problems in heightening gravity dams: worsening of dam heel stress; opening of joint-face between old and new concrete; and cracking of the downstream face of dams. The authors analyzed the reasons of these problems and proposed some solutions. In a 3-D numerical simulation of heightening the gravity dam of the Danjiangkou project, a temperature control method was applied and its feasibility to solve the problems were discussed. The result shows that, by proper temperature control, the heel stress situation could be improved and most part of the joint-face between old and new concrete could be kept in an integral state.